This invention relates to electrical outlets having improved characteristics of safety and durability. More, specifically, this invention relates to safety receptacle electrical outlets that have jacketed internal switches for improved durability and ease of insertion of an electrical plug.
It has been recognized for many years that an electrical outlet can constitute a hazard under certain circumstances and as to certain individuals, notably children, but also adults. Because the conventional outlet normally has two or more energized, electrically conductive contact surfaces, which are rather easily reached through openings in an insulating cover plate, insertion of a pin, scissors or other electrically conductive device can result in serious shock.
The recognition of this and similar problems has resulted in numerous efforts to provide a safer outlet, and some of these efforts are illustrated in the following United States patents: U.S. Pat. No. 2,540,496 to Sperrazza; U.S. Pat. No. 2,826,652 to Piplack; U.S. Pat. No. 3,617,662 to Miller; U.S. Pat. No. 3,775,726 to Gress; U.S. Pat. No. 3,990,758 to Petterson; U.S. Pat. No. 4,148,536 to Petropoulsos et al.; U.S. Pat. No. 4,271,337 to Barkas; U.S. Pat. No. 5,320,545 to Brothers; U.S. Pat. No. 5,374,199 to Chung; U.S. Pat. No. 6,111,210 to Allison.
Conventional safety outlets employ a pair of contacts within the outlet housing that operate to close the electrical circuit when the plug blades or prongs are inserted into the outlet. These devices have a wire leading to each of the contacts, which are positioned near the prong apertures in the outlet, and the wires are in turn connected to a power source. Each contact is adjacent a switch that is generally an arm that extends across the outlet from the opposite aperture. For example, the switch arm for the hot contact extends from the neutral aperture across the outlet to the hot contact. Each switch arm has an angled surface at its respective aperture and a conductive surface attached at the end. When a plug blade (or similar object) is inserted into the respective aperture, each arm moves laterally to allow the conductive surface to engage the contact for the other aperture, thus supplying power to each aperture. Therefore, for power to be supplied to both female elements, blades must be inserted into both apertures. As will be recognized, insertion of a foreign object into one female element presents no danger because that insertion only energizes the other element into which nothing has been inserted. For a more complete description of such a system, see U.S. Pat. No. 4,271,337 to Barkas, the entire contents of which are herein incorporated by reference.
While this is clearly a valid concept insofar as safety is concerned, the structure of the conventional devices has certain disadvantages, largely associated with normal usage of the outlet. First, it can be seen that the devices generally, due to manufacturing cost benefits, have plastic arms for the switches. Therefore, when prongs from a plug are repeatably inserted into the electrical outlet, the metal prong wears away a portion of the plastic arm. Over the life of the outlet, the arm can be damaged to the point where the switch is no longer operational, shortening the life of the outlet. Second, the plastic surface can cause significant friction with the metal prong, making it difficult to operate the switch and thereby difficult to achieve the intended result of supplying electrical power to the intended device.
Accordingly, it is an object of the present invention to provide an electrical receptacle having switched power circuits to reduce electrical shock hazard resulting from insertion of conductive foreign objects into the receptacle.
Another object of the present invention is to provide an electrical receptacle in which operating arms for the switches are laterally movable to expose the female conductive elements of the outlets by the plug blades, opening the switches before the blades engage the female elements.
A still further object of the present invention is to provide an electrical receptacle having a switch with low kinetic and static friction, for easy insertion of a plug and smooth responsive movement of the switch.
Yet another object of the present invention is to provide an electrical receptacle having a switch that is wear resistant for durability and increased outlet life.
These objects are basically obtained by an electrical receptacle for use with a power source, comprising a contact for making an electrical connection between the power source and a prong of an electrical plug, at least one switch being in series between the contact and the power source, and a resilient, smooth member covering at least a portion of the at least one switch, the switch being normally in the closed position and moving in a direction from the closed position to the open position due to a force applied to the resilient, smooth member covering at least a portion of the at least one switch by the prong of the electrical plug when the prong of the electrical plug is inserted into the electrical receptacle and contacts the resilient, smooth member.
Other objects, advantages and salient features of the invention will become apparent from the following detailed description which, taken in conjunction with the annexed drawings, disclose a preferred embodiment of the invention.